How Do I Simplify the Function f(x) = cos(x)(3cos(3x)) + (sin(3x))(-sin(x))?

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SUMMARY

The function f(x) = cos(x)(3cos(3x)) + (sin(3x))(-sin(x)) can be simplified by clarifying the expression with proper parentheses. The correct interpretation is f(x) = cos(x) * 3cos(3x) - sin(3x) * sin(x). Evaluating f(pi/6) becomes straightforward, as cos(3*pi/6) equals 0 and sin(3*pi/6) equals 1, leading to f(pi/6) = 0.

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Gill
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hey, i need to simplify this, and I am having a brain fart:confused: ...can u help me?

f(x)= cosx(3cos3x) + (sin3x)(-sinx)

i then have to find f(pi/6), but I am hoping i can do that once this is simplified...

thanks
Gill
 
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Gill said:
hey, i need to simplify this, and I am having a brain fart:confused: ...can u help me?
f(x)= cosx(3cos3x) + (sin3x)(-sinx)
i then have to find f(pi/6), but I am hoping i can do that once this is simplified...
thanks
Gill

I wonder you made a typo... is cosx(3cos3x) \cos(x*3\cos(3x)) or \cos(x)*3\cos(3x)? Please place braces and it will clarify. But as for f(pi/6), it looks easy in any typo cases, because \cos(3*\pi/6) = 0, \sin(3*\pi/6) = 1 :smile:
 

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